Reviewing the historical development of media agenda-setting theory suggests that topics emphasized by the mass news media become the topics people think are most important. The vast majority of agenda-setting studies, however, rely on aggregate measures of media and public agendas, and produce very little support for the original theory as there is no adequate theoretical framework. Furthermore, although recent developments in North American and British research have moved agenda-setting theory away from a functionalist and effects perspective, the theory and methods can still be criticized. Future agenda-setting research should focus on researchers' versus various publics' definitions of media and public agendas, as well as the nature of the communication process and public opinion. (Thirty-four references are included.) (PRA)